Linear light arrays are desirable for use when an specific long, narrow target area must be illuminated. One such use is for illumination of a continuous web in a web manufacturing inspection system. A web is any material which is manufactured in a single continuous sheet, such as paper and cloth. The web typically passes through a web inspection station that analyzes the web for defects. Cameras are positioned along the width of a web, with each camera taking images of a specific portion of the width of the web. Defects in the web, including discolorations, holes and tears, are identified as inconsistences in the images. Thus, the analysis depends upon consistent lighting of the web. Although the analysis may correct for minor lighting variations, dark spots caused by defective or inconsistent lighting may result in a false identifications of defects.
A number of companies manufacture modular LED linear arrays. However, these LED linear arrays often are of a fixed length that are not sufficiently long to illuminate a target width. Linear arrays that are extensible use modules that, when connected together, result in gaps between the modules so that the illumination is not uniform. In addition, the brightness of the existing illumination arrays are limited, and the focus of the light is not controllable. Some product offerings consist of LED circuit cards only, requiring the end user to construct a housing, structural mountings, and cooling provisions. Typical prior art illumination sources do not provide sufficient provisions for heat flow away from the illumination source. In addition, these products do not have power supply distribution provisions, and are not sealed for use in extreme environments.
Therefore, a need exists for an illumination source which is compact, energy-efficient and indefinitely extensible, and which combines the reliability advantages of light emitting diodes (LEDs) with the brightness of conventional lighting for use in direct lighting applications or for backlighting for translucent materials. A need exists for an illumination source that includes LED printed wire board segments that are mountable on an inner mounting base, wherein the LED printed wire board segments are configured to form a uniform illumination line of any length. A further need exists of an illumination source that includes an integral base in contact with the inner mounting base which serves as a heat sink and provides structural support for the illumination source, and which includes channels and cavities for cooling the illumination source and for housing power cables.